Headers on agricultural harvesters gather and cut the crops that are harvested. A typical header is an elongate laterally extending structure, typically 15-40 feet wide, that is supported on a feeder arm located on the front of the harvester vehicle. The header is vertically moveable using hydraulic cylinders that are coupled to the feeder arm at their forward ends and to the chassis of the harvester vehicle at their rear ends. The operator selectively raises and lowers the feeder arm and the header attached thereto by adjusting the length of the piston in the hydraulic cylinders.
In some instances, the hydraulic cylinders may not include hydraulic circuits to actively retract the pistons and lower the header. Instead, they rely on the considerable weight of the header to do that. They include hydraulic circuits that fill the head end of the cylinder to extend it, thus raising the header. When hydraulic fluid is released from the head end of the cylinders, the weight of the header and feeder house are sufficient to retract the cylinders. There is nothing to protect against or prevent the sudden downward fall of the header and feeder arm in the event the hydraulic system should fail or leak.
Occasionally, it becomes necessary to service the header or feeder arm, or to otherwise obtain access under the feeder arm. This of course creates the potentially hazardous situation of putting the operator or the maintenance personnel under a very large and heavy piece of farming equipment should the hydraulic cylinders fail. To minimize this risk, many harvesters have been outfitted with a safety stand. In a typical arrangement, the safety stand is a simple mechanical device, which pivots into place to physically prevent the hydraulic cylinder from retreating. The safety stand is essentially an elongated steel or iron lock out device, pivotally attached at one end to the header end of the piston of the hydraulic cylinder. When deployed, the lock out device is rotated into position such that it runs substantially parallel to the extended piston rod, and the end of the safety stand closest to the chassis physically engaged the header end of the hydraulic cylinder. The safety stand in this position allows only slight movement downward, until it physically engages the cylinder end to prevent further movement. In this position, the piston is physically incapable of further retreat into the cylinder. The header and feeder arm, accordingly stay in an upright position facilitating access underneath. When not in use, the safety arm is rotated upward and secured out of place, allowing free movement of the piston within the cylinder. One or more such hydraulic cylinders may be used on a given harvester, and one or more corresponding safety stands may be employed.
The current design has several shortcomings. The operator cannot engage the safety stand from inside the harvester vehicle. Current designs require the operator to raise the feed arm, climb out of the vehicle, lower the safety stand, climb back into the vehicle, lower the feed arm until the safety stand catches, and then to climb back out to perform the service required. All of this is hard on the operator who may have to climb up and down several times, which in addition to taking valuable time is also physically demanding.
Additionally, the operator has no way of knowing, from the cabin, whether or not the safety stand has been properly engaged. If the safety stand is engaged while the piston is not sufficiently extended, the end of the safety stand will not be in position to engage the cylinder end, but rather will ride along the surface of the cylinder.
Finally, if for some reason the safety stand fails, or is improperly deployed, there is no secondary safety feature to stop the feeder arm from dropping fully to the ground, should the hydraulics fail.
These and other problems exist in the current safety stand used in feeders and harvesters. A better, safer way is needed to protect our farmers and maintenance personnel in the field.